Breast cancer continues to be the second leading cause of death for women between the ages of 40 to 55 in America. The number of women developing breast cancer has increased tremendously from 1:20 in 1960 to 1:7 today. Epidemiological studies estimate that one in eight women will develop breast cancer during their lifetimes. Moreover, one in five women with breast cancer will die of the disease despite the considerable advances in treatment. According to the American Cancer Society, in 2007, an estimated 178,480 new cases and 40,460 deaths from breast cancer in women are expected to occur in the United States. Breast cancer development in men is also increasing. Given these circumstances, early detection of breast cancer is considered an important prognostic factor. Ideally, death from malignancy rather than its lack of detection should be the point of reference in evaluating any screening program.
Breast cancer occurs when cells in the breast begin to grow out of control and invade nearby tissues or spread throughout the body. It is one of the leading causes of cancer death in women. Mammography is the most commonly used screening modality for the early detection of breast cancer. However, mammography is of limited value in young and premenopausal women because denser breast tissue produces mammographic images which are difficult if not impossible to interpret. Therefore, there is a need to develop novel and more effective screening strategies with a high sensitivity and specificity.
Cancer development in tissue below the breast surface appears to generate an increase in the temperature on the breast surface. For several decades medical researchers around the world have struggled to find an accurate method for interpreting thermal circadian data related to tumor growth in the breast, and using this as a detection modality. It is recognized that the breast exhibits a circadian rhythm that is reflective of its physiology. Areas of mammalian tissue adjacent to carcinomas exhibit increased temperatures from that exhibited by non-adjacent, non-cancerous areas. The temperature of a cancer-affected area can fluctuate several degrees Centigrade from normal tissue; this difference having been demonstrated while monitoring such an area for a 24-hour period. The relationship between breast skin temperature and breast cancer has been documented and it has been found that the differences between the characteristics of rhythmic changes in skin temperature of clinically healthy and cancerous breasts were real and measurable.
Currently mammography is considered the gold standard as a screening tool for the early detection of breast cancer. Unfortunately, wide variations exist in its sensitivity and specificity in published reports. Mammographic sensitivity varied from 100% in fatty breasts to 4% in extremely dense breasts, as evidenced by a recent study. As a consequence, other technologies have been used in an effort to complement mammography. Magnetic resonance imaging (MRI) has been shown to be more sensitive in the early detection of occult breast cancers, particularly in pre-menopausal women for whom the sensitivity of mammography is compromised, but with less specificity and greater cost. Additional modalities are still under development, such as electrical impedance scanning (EIS), mammary ductoscopy (MD), and proteomics of nipple aspirate fluid (NAF) and serum. In spite of these advances, women in the United States are subjected to numerous unnecessary breast biopsies each year because of the inadequacies of the aforementioned breast cancer detection modalities' inability to separate benign from cancerous lesions.
Recent reports indicate that MRI is able to detect cancer in the contralateral breast even when such cancers were missed by mammography or in clinical examination at the time of the initial breast examination. In addition, MRI has been proven to be a better screening tool for women with genetic mutations of the BRCA1 or BRCA2 genes, and in those women with a strong family history of breast cancer. Although the sensitivity of MRI is better than that of mammography, the technique is flawed by a lower specificity and a far greater expense. However, recently, the American Cancer Society announced a change in its breast cancer screening recommendation guidelines, recommending that women with high genetic risk (such as those who have mutation in the BRCA1 or BRCA2 genes or those with a strong family history of breast cancer) be screened with magnetic resonance imaging.
An additional source of concern relates to the fact that radiologists fail to detect cancer in up to thirty percent of patients with breast cancer despite the fact that the malignancies missed by the radiologists are evident in two thirds of the mammograms. There is a need to further assist radiologists, surgeons and other physicians in detecting, diagnosing, successfully biopsing, and operating on precancerous and cancerous conditions.
The establishment and growth of most tumors depends on the successful recruitment of new blood vessels into and around the tumor cells. This process, also known as angiogenesis, is dependent on the production of angiogenic growth factors by the tumor cells. Angiogenesis results in a more constant blood flow to the area of the tumor, which increases the local temperature in the area surrounding the tumor in comparison to normal breast tissue.
The superficial thermal patterns measured on the surface of the breast are related to tissue metabolism and can serve as a means to visualize activity within the underlying tissue. Such thermal patterns change significantly as a result of normal phenomena including the menstrual cycle, pregnancy and, more importantly, the pathologic process itself. Cancer development, in most instances, represents the summation of a large number of mutations that occur over years, each with its own particular histologic phenotype that can be seen in pre-menopausal mastectomy specimens. Cancer development appears to generate its own thermal signatures, and the complexity or lack thereof may be a reflection of its degree of development.
Thermographic technology was originally introduced to complement mammography because it was felt that a thermogram of the breast was able to detect breast cancer development up to 10 years earlier than most conventional modalities. However, the accuracy of thermography has remained questionable due to a number of factors, such as the symmetry and stability of the breasts' temperature during the menstrual cycle and temperature fluctuations caused by the use of oral contraception.
One prior device used for detecting cancer is a brassiere that includes a plurality of temperature sensors, an analog multiplexer circuit, a control circuit, a sample and hold circuit, an analog/digital converter, a buffer register, a storage register, a clock and a data logger. The device allows for the storage of temperature readings in a digital form. This digital data may be uploaded to the data logger which converts the digital signals to decimal form so that the temperature differences may be read and analyzed by a supervising physician and the problems associated with such devices are stated in commonly owned U.S. Pat. No. 6,389,305.
Other devices use a passive thermographic analytical apparatus that provide a direct readout of the results through analysis of a thermographic radiation pattern of the human body. Such devices are unable to detect small tumors on the order of less than 0.5 cm and possibly other larger tumors and certain types of cancers, and do not take into account the chaotic fluctuation of normal body temperatures over time and between locations on the body.
Many cancers are diagnosed too late; successful treatment is more attainable if the cancer is found at early stages. Other devices described in U.S. Pat. Nos. 6,389,305, 5,941,832 and 5,301,681 have met with some limited success, but are yet to provide an optimal breast cancer detection device. There remains a need to improve the method and device for detection of potentially cancerous conditions in breasts.